Implementation and Integration of Prehospital ECGs Into Systems of Care for Acute Coronary Syndrome
AHA Scientific Statement
Implementation and Integration of Prehospital ECGs Into
Systems of Care for Acute Coronary Syndrome
A Scientific Statement From the American Heart Association
Interdisciplinary Council on Quality of Care and Outcomes Research,
Emergency Cardiovascular Care Committee, Council on Cardiovascular
Nursing, and Council on Clinical Cardiology
Henry H. Ting, MD, MBA, Chair; Harlan M. Krumholz, MD, SM, FAHA, Co-Chair;
Elizabeth H. Bradley, PhD; David C. Cone, MD; Jeptha P. Curtis, MD;
Barbara J. Drew, RN, PhD, FAHA; John M. Field, MD; William J. French, MD;
W. Brian Gibler, MD; David C. Goff, MD, PhD, FAHA; Alice K. Jacobs, MD, FAHA;
Brahmajee K. Nallamothu, MD, MPH; Robert E. O’Connor, MD; Jeremiah D. Schuur, MD, MHS
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C
linical case: A 58-year-old woman called 9-1-1 with
acute onset of chest pain that had persisted for 30
minutes. She had a history of hypertension, hyperlipidemia, and type 2 diabetes mellitus but no previous history
of myocardial infarction or heart failure. Her medications
included aspirin, atorvastatin, lisinopril, and metoprolol.
Paramedics were dispatched, and a prehospital ECG demonstrated 3- to 4-mm ST-segment elevation in leads I,
aVL, and V2 through V6 (Figure 1). Her examination
revealed a regular pulse of 90 bpm, a blood pressure of
100/60 mm Hg, clear lungs, and normal heart sounds with
no murmurs. Paramedics interpreted the prehospital ECG
and activated the catheterization laboratory en route to the
hospital. On hospital arrival, the patient was transported
directly to the catheterization laboratory. Coronary angiography demonstrated an occluded proximal left anterior
descending artery, which was successfully treated with
balloon angioplasty and a stent. The pertinent time intervals were as follows: paramedic dispatch to balloon time,
56 minutes; paramedic arrival at the scene to balloon time,
46 minutes; hospital door to balloon time, 23 minutes. Her
biomarkers revealed a peak troponin T of 2.42 ng/mL and a peak
creatine kinase muscle-brain isoenzyme of 26.8 ng/mL. An
echocardiogram demonstrated normal left ventricular ejection
fraction of 55%, with mild anterior hypokinesis, and the patient
was discharged on hospital day 3.
Current Guidelines for Prehospital ECGs
Among Patients With ST-Segment–Elevation
Myocardial Infarction
American Heart Association national guidelines,1–3 as well as
other consensus and scientific statements,4 –11 recommend
that emergency medical services (EMS) acquire and use
prehospital ECGs to evaluate patients with suspected acute
coronary syndrome. Despite these recommendations, prehospital ECGs are used in fewer than 10% of patients with
ST-segment– elevation myocardial infarction (STEMI),12,13
and this rate has not substantially changed since the mid1990s. Furthermore, even when a prehospital ECG is acquired, the information is often not effectively translated into
action and coordinated with hospital systems of care to
decrease delays in reperfusion therapy.13 The purpose of this
article is to summarize evidence concerning the benefits of
using prehospital ECGs, review barriers and challenges to
routine use, and recommend approaches to enhance their
effectiveness for improving quality of care for patients with
acute coronary syndromes.
The American Heart Association makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside
relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required
to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.
This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on July 2, 2008. A single reprint is
available by calling 800-242-8721 (US only) or by writing the American Heart Association, Public Information, 7272 Greenville Ave, Dallas, TX
75231-4596. Ask for reprint No. 71-0454. A copy of the statement is also available at http://www.americanheart.org/presenter.jhtml?identifier⫽3003999
by selecting either the “topic list” link or the “chronological list” link. To purchase additional reprints, call 843-216-2533 or e-mail
kelle.ramsay@wolterskluwer.com.
Expert peer review of AHA Scientific Statements is conducted at the AHA National Center. For more on AHA statements and guidelines development,
visit http://www.americanheart.org/presenter.jhtml?identifier⫽3023366.
Permissions: Multiple copies, modification, alteration, enhancement, and/or distribution of this document are not permitted without the express
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(Circulation. 2008;118:1066-1079.)
© 2008 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.108.190402
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Prehospital ECGs for Acute Coronary Syndrome
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Figure 1. Prehospital ECG.
What Are the Benefits of Using Prehospital
ECGs in Patients With STEMI?
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Multiple studies have demonstrated the benefits of prehospital ECGs for decreasing door-to-drug time and door-toballoon time in patients with STEMI.12–30 The direction and
magnitude of the time savings are clinically relevant, resulting in an approximately 10-minute decrease in door-to-drug
time and 15- to 20-minute decrease in door-to-balloon
time.12,13 However, these time savings may not reflect the full
potential of prehospital ECGs to decrease delays in reperfusion therapy. In fact, studies have shown further reductions in
door-to-balloon time when prehospital ECGs are used to
activate the catheterization laboratory while the patient is en
route to the hospital.31–37
For patients transported by EMS without prehospital ECG,
delay from symptom onset to reperfusion therapy, which
reflects the overall period of ischemic injury, can be divided
into 4 time intervals: (1) symptom onset to EMS arrival, (2)
EMS arrival to hospital arrival, (3) hospital arrival to ECG,
and (4) ECG to reperfusion. Prehospital ECG programs, if
effectively implemented and coordinated with hospital systems of care, would be expected to decrease the latter 3 time
intervals (Figure 2). The second interval is composed of time
from first medical contact by EMS to hospital door, and EMS
personnel may behave with more urgency if a diagnosis of
STEMI has been made in the field. The third interval is
essentially eliminated with a prehospital ECG. The fourth
interval can be decreased by advanced notification of the
hospital to receive and evaluate the patient, to activate the
catheterization laboratory while the patient is en route, or to
bypass the emergency department and transport the patient
directly to the catheterization laboratory. Scholz and colleagues reported the impact of prehospital ECGs on these
time intervals from 114 patients with STEMI treated within
an integrated system of care.38 The system consisted of
acquiring a prehospital ECG by emergency responders (in
Germany, this was generally a physician), transmitting the
prehospital ECG to a fax machine at the percutaneous
coronary intervention (PCI) hospital cardiac intensive care
unit, activating the catheterization laboratory en route if
STEMI was diagnosed, and bypassing the emergency department when the catheterization laboratory team was on-site.
Pertinent time intervals were collected for 1 year. Comparing
performance in the last quarter of implementing this system
with the first quarter (reference group), the time spent at the
scene decreased from 25 to 19 minutes, time spent in the
Reperfusion goals: EMSEMS-toto-drug < 30 min; EMSEMS-toto-balloon < 90 min; Symptom
onsetonset-toto-reperfusion < 120 min (text adapted from reference 1)
(1) PH ECG interpreted by EMS or transmitted by cell phone to hospital
(2) Pre-arrival activation of catheterization lab
Onset of
Symptoms
EMS Arrival
Prehospital
Electrocardiogram
Hospital
Arrival
Reperfusion
Increasing loss of myocytes
Figure 2. Reperfusion time goals for patients with ST-segment– elevation myocardial infarction.
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‘Table 1.
September 2, 2008
Models for interpreting Prehospital ECGs
Method of Interpreting Prehospital
ECG
Pros
Cons
Computer algorithm interpretation
Rapid, easy
No wireless network or technology
requirements
False-positive and false-negative rates higher than
physician interpretation
Paramedic interpretation
Rapid, easy
No wireless network or technology
requirements
Requires intensive education and quality
assurance program
More complex in communities with multiple EMS
providers and agencies
Wireless transmission and physician
interpretation
Theoretically, lowest rate of false-positives and
false-negatives
Medical oversight can provide guidance on
destination hospital and treatment en route
New technology requirement for EMS providers
and hospital
Reliable wireless network Transmission unit on
ambulance
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Receiver station unit at hospital
Smartphones for physicians
Requires system to ensure immediate
interpretation by physician
Transmission failures
EMS indicates emergency medical services.
emergency department decreased from 14 to 3 minutes, time
from arterial access to balloon decreased from 21 to 11
minutes, door-to-balloon time decreased from 54 to 26
minutes, and first medical contact to balloon time decreased
from 113 to 74 minutes. The authors also concluded that
systematic, quarterly feedback on performance to cardiology,
emergency department, and EMS stakeholders was an important component in improving prehospital and hospital processes of care.38
Can EMS Providers Acquire
Prehospital ECGs?
A survey found that 90% of EMS systems serving the 200
largest cities in the United States had 12-lead ECG equipment
available in their ambulance systems.39 EMS providers can
rapidly acquire diagnostic-quality prehospital ECGs with an
average increase of 5 to 6 minutes in the on-scene time
interval.14 –16,28,40 – 49 To acquire diagnostic-quality prehospital
ECGs, a valuable strategy is to educate EMS providers about
the importance of careful patient positioning and lead placement. Movement artifact, lead misplacement, and poor skin
contact can result in poor-quality tracing that can be misinterpreted by algorithms or EMS providers.
One study, which used data from the National Registry of
Myocardial Infarction between 1994 and 1996, found that
patients with prehospital ECGs had time intervals that were
20 minutes longer from symptom onset to hospital arrival.12
This finding was difficult to interpret, however, as there was
no measure of how long the prehospital ECG required and
potential selection bias in who received a prehospital ECG.
For example, patients who had a longer transport distance
may have received a higher rate of prehospital ECGs as
compared with those with a shorter transport distance. An
analysis of the National Registry of Myocardial Infarction
between 2000 and 2002 found that patients with prehospital
ECGs did not have longer times from symptom onset to
hospital arrival.13
Can EMS Providers Reliably Interpret or
Communicate Prehospital ECGs?
Several studies have examined the feasibility of EMS providers identifying STEMI using prehospital ECGs with or
without wireless transmission.20,36,50 –58 The pros and cons for
computer algorithm interpretation, paramedic interpretation,
and wireless transmission for physician interpretation of
prehospital ECGs are summarized in Table 1. There are no
data to compare the effectiveness of these different approaches for diagnostic accuracy or quality of reperfusion
therapy delivered to patients with STEMI. The choice of
which option to use may also be limited by the specific
resources available in the community or its local geography.
Studies have also shown that paramedics with specific
ECG training can reliably interpret prehospital ECGs without
transmitting to a hospital or physician. Trained paramedics
can identify STEMI with sensitivity ranging from 71% to
97% and specificity ranging from 91% to 100%,15,16,59 – 65 and
with good agreement between paramedics and emergency
department physicians ( ranging from 0.59 to 0.73).20,60,64
The sensitivity (97%) and specificity (91%) of trained paramedics to interpret prehospital ECGs and diagnose STEMI
was particularly high in one study, which included a 2-day
training seminar.62 A study of this issue, conducted in the
United States with 151 patients with suspected acute myocardial infarction transported by a large urban EMS system,
found that trained paramedics had 80% sensitivity and 97%
specificity in diagnosing STEMI with prehospital ECGs, with
good agreement between paramedics and emergency physicians (⫽0.73).64
Ting et al
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Alternatively, prehospital ECGs can be transmitted by
EMS for physician interpretation to drive decision making,
but this approach has been limited by technology requirements for rapid and reliable transmission of prehospital
ECGs. Two pilot studies have demonstrated that wireless
transmission of prehospital ECG is feasible.36,55 In the Timely
Intervention in Myocardial Emergency–Northeast Experience
(TIME-NE) conducted in Concord, NC, 24 patients with
STEMI had successful wireless transmission of prehospital
ECGs to a hospital receiving station and the on-call cardiologist’s smartphone.55 The on-call cardiologist then decided
whether to activate the catheterization laboratory on the basis
of the prehospital ECG. Median door-to-balloon time decreased in this study to 50 minutes as compared with 101
minutes for historical controls; however, there were 19
patients with STEMI who experienced failed wireless transmission. In the ST-Segment Analysis Using Wireless Technology in Acute Myocardial Infarction (STAT-MI) study
conducted in Newark, NJ, 80 patients had prehospital ECGs
transmitted using a wireless cellular phone network to a
secure hospital central server and to the on-call cardiologist’s
smartphone.36 This model had no transmission failures; median time from prehospital ECG acquisition to availability on
the remote server was 2 minutes and on the smartphone was
4 minutes. The door-to-balloon time was 80 minutes with use
of prehospital ECGs, as compared with 146 minutes for
historical controls without use of prehospital ECGs. In
geographic regions with reliable wireless network coverage,
wireless transmission of prehospital ECG for physician interpretation is feasible and reliable; however, current wireless
networks can fail to transmit or encounter significant delays
in up to 20% to 44% of cases as a result of wireless “dead
Prehospital ECGs for Acute Coronary Syndrome
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zones” in a moving ambulance or in rural areas with sparse
coverage.50,55,62,66,67
Wireless transmission prehospital ECG systems are commercially available from Medtronic36,57 (Minneapolis, Minn),
Welch Allyn55 (Beaverton, Ore), Zoll Medical30 (Chelmsford,
Mass), and Phillips Healthcare (Andover, Mass). These
systems acquire the prehospital ECG and automatically transmit the data using Bluetooth protocol to a nearby cellular
phone. The cellular phone functions as a router to transmit the
data to a central receiving station and smartphones via a
wireless cellular network or wireless local area network
(IEEE 802.11).68 –71 A novel approach using camera phones
with multimedia messaging service has been proposed and
tested in 10 patients.72 A camera phone obtains a digital
picture of the prehospital ECG paper printout and wirelessly
transmits the picture to an e-mail account, and the ECG image
can be viewed on any multimedia messaging service– capable
device, such as a computer or smartphone. This approach
may be a simple, low-cost, and innovative technology73 to
communicate diagnostic image data and warrants further
study for feasibility in real-world practices.
Can EMS and Hospitals Organize Systems to
Effectively Use Prehospital ECGs?
EMS and hospitals should organize efficient systems of care
for patients with STEMI from the prehospital phase of care to
hospital arrival and reperfusion therapy in the hospital phase
of care. The typical current process2 for emergency cardiac
care initiated by a 9-1-1 call is contrasted with the ideal
process in Figure 3. Historically, EMS providers have been
trained to follow these steps in evaluating patients with chest
pain in the field: (1) assess airway, breathing, circulation, and
Figure 3. Current versus ideal processes to integrate prehospital ECGs into systems of care.
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vital signs; (2) obtain focused history and examination; (3)
assess cardiac rhythm; (4) initiate treatment with oxygen,
aspirin, nitroglycerin, and morphine and insert intravenous
line; (5) recommended: acquire 12-lead prehospital ECG at
the scene, after the patient is transferred to the ambulance, or
while en route to the hospital. Because the 12-lead ECG
represents the critical data for diagnosis and decision making
in patients with chest pain, it should be prioritized and
performed as early as possible at the scene. If a STEMI is
identified on the prehospital ECG, then scene times should be
minimized, with expedited transport to the hospital. Moreover, if the prehospital ECG is communicated to the destination hospital shortly after first medical contact with EMS
providers, then the hospital will have more time to prepare for
the patient.
The information from a prehospital ECG and advanced
notification should lead to efficient action by hospital systems
of care to deliver prompt reperfusion therapy, including
preparing to receive and evaluate the patient, activating the
catheterization laboratory while the patient is en route, or
bypassing the emergency department and transporting the
patient directly to the catheterization laboratory.32,37,74 If
patients are evaluated in the emergency department, the
evaluation should be streamlined by having a physician
and necessary resources (eg, translators, nurses) ready
before patient arrival, following a standard protocol for
treatment, and minimizing physical movement, such as
transferring between stretchers. Although bypassing the
emergency department may be intuitively faster, concerns
have been raised about processes for obtaining informed
consent, patient safety, and consideration of alternative
diagnoses (eg, aortic dissection, intracranial hemorrhage)
or other false-positives that may account for the STsegment elevation on the ECG in up to 10% to 15% of
patients.75–77 Furthermore, during off hours,78,79 the catheterization team may not have arrived at the hospital
before the ambulance, and the patient will need to be
observed in a critical care setting until the catheterization
laboratory is ready to receive the patient.
Table 2.
Can Regional Networks of Hospitals Organize
Systems to Effectively Use Prehospital ECGs?
Patients with STEMI who require interhospital transfer experience substantial delays with a median first hospital
door-to-balloon time of 180 minutes.80 In the United States,
regional networks of hospitals and systems of care have been
implemented and evaluated to improve time to reperfusion
therapy for patients who initially present to a community
hospital without on-site PCI capability.35,81– 83 Similar, but
broader systems of optimizing reperfusion therapy across
populations have also been in place in Europe for several
years.24,84,85 European systems often have a physician in the
ambulance, a central dispatch center for ambulances, and
highly organized regional prehospital care, which stands in
contrast to the disorganized, competitive environment in the
United States.
Prehospital ECGs can play an important role for triage of
patients in a regional network of hospitals, and the two
models proposed include prehospital triage versus interhospital transfer.3,11,74,86 – 89 The prehospital triage model transports patients with STEMI to the closest PCI center and
bypasses hospitals without PCI capability. The interhospital
transfer model focuses on advanced notification and efficient
transfer of patients from non-PCI hospitals to PCI centers.11
Several key factors, including distance, urban versus rural
location, collaborative versus competitive relationships between hospitals, and variability of EMS providers, influence
which model is best suited for specific regional populations.
An analysis of the US Census Survey and the American
Hospital Association Annual Survey showed that 80% of the
adult population live within 60 minutes of a PCI-capable
hospital, and only 5% live farther than 90 minutes from one.90
However, there are still 20% of the adult population and large
geographic areas that do not meet this standard. One model of
regionalized STEMI care does not preclude the other. Both
can coexist within a single network and are often driven by
specific resources available within a community and local
geography. No data comparing the models exist, and potential
unintended consequences, such as exceptionally long delays
to reperfusion, should be monitored.10,91
Comparison of Existing Prehospital ECG Programs
Location
Prehospital ECG Interpretation
Activate Catheterization Lab en Route to
Hospital
Bypass Non-PCI
Hospitals
Boston64,92
Paramedic interpretation
Yes (activation by emergency department
physician based on paramedic
interpretation)
Yes (for all patients with
“definite STEMI” or
“possible STEMI”)
Los Angeles County76,87
Computer algorithm interpretation
Yes (activation by emergency department
physician based on computer
algorithm interpretation)
Yes (for all patients with
acute MI)
North Carolina83
Mixed (used computer algorithm interpretation,
paramedic interpretation, or wireless
transmission)
Mixed (activation by paramedics or
emergency department physician)
Mixed (paramedics
occasionally diverted
patients with STEMI
to nearest PCI
hospital)
Ottawa65,96
Paramedic interpretation
Yes (activation by paramedic through a
central page operator)
Yes (for all patients with
STEMI)
PCI indicates percutaneous coronary intervention; MI, myocardial infarction; and STEMI, ST-segment– elevation myocardial infarction.
Ting et al
How Have Prehospital ECGs Been
Incorporated Into Existing Systems of Care?
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Many communities are implementing prehospital ECG programs that are in varying stages of development, and Boston,
Los Angeles, North Carolina, and Ottawa (Canada) provide
important contrasts (Table 2). The Boston EMS program, one
of the country’s first, involves municipal paramedics trained
to interpret and categorize prehospital ECGs as definite
STEMI, possible STEMI, or nondiagnostic.9,64,92 Patients
with definite STEMI or possible STEMI are triaged to the
closest PCI hospital, and the former are brought directly to
the catheterization laboratory and the latter are evaluated
in the emergency department. The emergency physician
decides whether to activate the catheterization laboratory
on the basis of the paramedic interpretation while the
patient is en route to the hospital. The Boston EMS
program covers a relatively small geographic area (⬍50
square miles) with 60 to 70 municipal paramedics, and
private EMS providers do not participate in the program.
In contrast, the Los Angeles County EMS program includes all EMS providers, an area of ⬎4000 square miles
with approximately 2500 paramedics working for 27 agencies.76,87 The variability and sheer numbers of EMS providers
to train in ECG interpretation were considered an insurmountable obstacle. The Los Angeles County EMS program
therefore relies on computer algorithm interpretation that
identifies ***ACUTE MI*** to prompt EMS transport of
patients to the closest PCI center (or STEMI receiving
center). The emergency physician decides whether to activate
the catheterization laboratory on the basis of the computer
algorithm interpretation while the patient is en route to the
hospital. A few hospitals in Los Angeles County have started
to pilot the feasibility of transmitting prehospital ECGs for
physician interpretation. Both the Boston and Los Angeles
programs are undergoing formal evaluation. There are also
ongoing clinical trials in other parts of the United States
evaluating the effectiveness of prehospital ECGs to decrease
first medical contact to balloon/drug times.93–95
The Reperfusion of Acute Myocardial Infarction in North
Carolina Emergency Departments (RACE) Investigators implemented a statewide approach to improve timeliness of
reperfusion therapy for patients with STEMI.83 The use of
prehospital ECGs was high, and prehospital ECGs were
acquired in 61% and 43% of patients with STEMI transported
by EMS to PCI hospitals and non-PCI hospitals, respectively.
However, the RACE program did not have standardized
procedures for when to acquire a prehospital ECG, who
would interpret the prehospital ECG, and how to integrate the
prehospital ECG with systems of care. Each hospital and
region decided how to interpret and integrate the prehospital
ECG based on available resources, geography, and decisions
by regional leadership.
The Ottawa citywide system, which included 1 PCI
center and 4 non-PCI hospitals located within 7 miles of
the PCI center, reported their 1-year experience in 344
patients with STEMI.96 The first hospital door-to-balloon
time was 69 minutes when paramedics acquired and
interpreted a prehospital ECG and bypassed non-PCI
hospitals as compared with 123 minutes when a prehospi-
Prehospital ECGs for Acute Coronary Syndrome
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tal ECG was not performed and the patient was initially
brought to a non-PCI hospital and required interhospital
transfer for primary PCI.
What Are the Barriers to Implementing
Successful Prehospital ECG Programs?
What Are the Costs and Benefits for Prehospital
ECG Programs?
Currently, there are no cost-effectiveness models to evaluate
this diagnostic technology from the different perspectives of
patients, hospitals, payors, and society.97 One study reported
that the incremental cost to upgrade prehospital ECG equipment to wireless capability was $16 100, which consisted of
$11 000 for a receiving station, $600 for cell phones, and
$4500 for data cables.57 The direct cost for prehospital ECG
equipment with monitoring and defibrillation capability
ranges from $9000 to $25 000, but this does not take into
account other direct and indirect costs for training, quality
assurance, and organizing complex EMS and hospital systems.8,98 Developing and implementing STEMI systems require substantial investment of resources that impact on the
value of acquiring and using the information provided by
prehospital ECGs. Comparative cost models for efficiently
acquiring, interpreting, and transmitting prehospital ECGs
within the context of STEMI systems will be informative and
valuable. Additionally, it will be important to compare the
development of STEMI systems of care with other healthcare
priorities, both in cardiovascular medicine and other
disciplines.
What Training and Maintenance of Competency
Do EMS Providers Need?
In the United States, EMS providers are trained to several
competency levels. Although the federal government (http://
www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.2a0771e91
315babbbf30811060008a0c/) has defined a standard curricula
for each of 4 levels (first responder, emergency medical technician [EMT]– basic, EMT-intermediate, and EMT-paramedic),99
many states use definitions and regulations that vary significantly between states as well as within a single state (rural versus
urban areas). The National Registry of EMTs (www.nremt.org),
the nation’s de facto “board” for certification, currently certifies
EMS personnel at the first responder, EMT-basic, EMTintermediate/1985, EMT-intermediate/1999, and EMTparamedic levels.
First responder roles are often provided by firefighters or law
enforcement officers.9 EMT-basic personnel provide basic life
support, including first aid, cardiopulmonary resuscitation, oxygen, and early defibrillation. EMT-intermediate and EMTparamedic personnel provide advanced life support, including
intubation and intravenous medications. Prehospital ECG acquisition has historically been limited to EMT-paramedic. The
current EMT-paramedic national standard curriculum99 includes
the following objectives intended to provide paramedics with a
basic understanding of the pathophysiology and ECG features of
acute myocardial infarction:
5–2.9 Identify the arterial blood supply to any given area of
the myocardium.
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September 2, 2008
5–2.22 Discuss the pathophysiology of cardiac disease and
injury.
5–2.34 Relate the cardiac surfaces or areas represented by the
ECG leads.
5–2.48 Recognize the changes on the ECG that may reflect
evidence of myocardial ischemia and injury.
5–2.78 Identify the ECG changes characteristically seen
during evolution of an acute myocardial infarction.
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The National Association of EMS Educators (www.naemse.
org) is presently revising all of the existing national standard
curricula for EMS with new standards. The initial draft of this
document, released in June 2007, includes 12-lead ECG
interpretation as a required competency for paramedics.
Currently, no standards exist regarding how much initial
and subsequent periodic education is required to achieve
and maintain competency in prehospital ECG interpretation. Also, there are no standard protocols for when and
what patient subsets to obtain a prehospital ECG, as well
as what to do with the data.
It has been proposed that prehospital ECG acquisition be
extended to EMT-basic and EMT-intermediate levels.9 A
preliminary study showed that EMT-basic personnel could
acquire, but not interpret, ECGs in a comparable amount of
time as compared with EMT-paramedics.100 Although rural
geographic areas without paramedic coverage could benefit
by extending prehospital ECG acquisition skills to EMTbasic personnel, this would require significant changes in
current curriculum, training, protocols, and policy.
EMS systems vary substantially with regard to configuration and structure, each using some combination of EMS
providers to deliver emergency medical care for rural, suburban, or urban communities. Physician oversight also varies,
with only a small number of large EMS systems having
full-time physician medical directors. Given the challenges
with EMS training, maintenance of competency,101–103 quality management, and medical oversight, there is no “one size
fits all” or even “one size fits most” solution.
How Will Patients With Acute Coronary
Syndromes Use EMS?
The reluctance of patients with acute coronary syndromes
to call 9-1-1 is a major obstacle to realization of the full
public health benefits of prehospital ECGs and organizing
systems of care. Prior studies have shown that 10% to 59%
of patients with chest pain use EMS104 –111 and less than
half of patients with STEMI use EMS versus self-transport
to the hospital.8,110 Studies have demonstrated that patients
with STEMI arriving by ambulance receive faster reperfusion therapy than those who arrive by self-transport,
particularly in busy, overcrowded emergency departments.112,113 Unfortunately, educational and media efforts
to increase EMS use have had limited success.114 Conversely, if substantially more patients with chest pain call
9-1-1, EMS and emergency department systems may need
to grow to provide adequate access and capacity.113,115–117
Efforts to increase the reach of prehospital ECG programs
will need to address the limited use of EMS by patients
with STEMI and the need to expand EMS capacity to meet
increased demand.
What Areas of Future Research Need
to Be Addressed?
How Will the Use of Prehospital ECGs Be
Measured and Assessed?
For the most part, current measures for assessing the use and
timeliness of reperfusion therapy in STEMI (eg, door-toballoon time) are hospital-based and therefore inadequate for
evaluating the effectiveness of prehospital ECGs. To evaluate
the incremental benefit of this technology, current hospitalbased measures (door-to-balloon time) would need to evolve
to patient-centered measures, such as first medical contact to
reperfusion or symptom onset to reperfusion. Current STEMI
guidelines recommend that the pertinent metric for quality of
reperfusion therapy are first medical contact to balloon ⬍90
minutes and first medical contact to drug ⬍30 minutes.3
Furthermore, we need to assess patient responsiveness after
onset of symptoms, appropriate use of EMS and EMS
responsiveness, EMS scene time to acquire prehospital
ECGs, and effective communication of this data to destination hospitals and its use in decision making about reperfusion therapy. There needs to be careful analysis of the
denominator or eligible population who should have received
a prehospital ECG versus those who actually received a
prehospital ECG. For providers to adopt the technology, an
improved understanding of how potential gains in rapid
reperfusion translate into improved clinical outcomes would
be ideal, as well as an understanding of the frequency of false
alarms and other unintended consequences. Real-world examples are particularly helpful in this regard, given the
wide-ranging approaches that different types of healthcare
systems—for example, urban versus rural—may require.
These examples would also be important for assessing the
overall value of this technology relative to the financial
investment in equipment, training, and organizing STEMI
systems.
How Will Prehospital ECGs Be Performed and in
Whom Should They Be Used?
There remains a poor understanding of who will acquire and
interpret prehospital ECGs and in whom these tests should be
performed. A direct comparison of diagnostic accuracy and
times for ECG interpretation by computer algorithm, paramedics, and emergency physicians or cardiologists would be
valuable. Most regions that use prehospital ECGs have
standard protocols for what types of symptoms should prompt
acquisition of the test, but the false-positive and falsenegative rates have been poorly characterized in general. It
would be valuable to understand the frequency of STsegment elevation from other causes,118 such as early repolarization, left ventricular hypertrophy, left bundle-branch
block, pericarditis, hyperkalemia, atrial flutter, Brugada syndrome, pulmonary embolism, and Prinzmetal angina, as
prehospital ECG programs are implemented.
It has been reported that approximately 5% of patients
with chest pain who are evaluated by EMS have
STEMI.59,76 The incremental value of this technology
when the number needed to treat is 20 for 1 patient who
benefits needs to be verified and elucidated in patients with
Ting et al
Prehospital ECGs for Acute Coronary Syndrome
more atypical symptoms, such as shortness of breath,
dizziness, or other atypical symptoms.
Table 3. Requirements for an Integrated Prehospital ECG
System of Care
How Will Prehospital ECGs Be Integrated Into
Practice Without Unintended Consequences?
EMS
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An important area of investigation is how the prehospital
ECGs can optimize decision making to triage patients to
destination hospitals with and without PCI capability. The
broad and diverse population of the United States poses
several challenges to establishing effective systems of care
for incorporating prehospital ECGs into routine clinical
practice. It is apparent that a one-size-fits-all approach is
neither practical nor ideal. The use of this technology
requires a careful assessment of the local needs and
resources within each community, with the overarching
goal to improve patient care and access, timeliness of
reperfusion therapy, and the proportion of eligible patients
who receive reperfusion.
A better understanding of the precise role of different
providers in the design of systems that use prehospital ECGs
is needed. How will the roles of EMS and emergency
physicians evolve for activating the catheterization laboratory? How will safeguards be established so that patients with
other life-threatening conditions that may mimic or complicate STEMI are not missed and care is not delayed? Investigators should be encouraged to explore both the benefits and
pitfalls of implementing a prehospital ECG program. There
may be unintended deleterious effects to patients, such as
longer scene times and overall longer time from symptom
onset to reperfusion.
What Policy Measures Should Be Adopted to
Encourage Use of Prehospital ECGs?
The healthcare system within the United States is not currently
organized in a way that encourages the adoption of prehospital
ECGs or regional systems of care for STEMI.90,119,120 Numerous
providers in the prehospital and hospital settings make it challenging to foster cooperation. For example, in many regions,
there are several private, for-profit EMS that are responsible
for evaluating and transporting patients. Successful implementation will require the inclusion of these providers and
may necessitate that prehospital ECGs are required by
regulation and are reimbursed. Currently, EMS reimbursement is typically based on 2 levels of care as well as
distances traveled, but EMS is not reimbursed for specific
services delivered, including a prehospital ECG. However,
it also is unclear whether expansion of reimbursement for
prehospital ECGs may lead to overuse and misuse.
Issues surrounding reimbursement are also fundamental to
hospitals. Cardiac patients are seen as lucrative, given the
high rate of invasive procedures associated with these conditions, and represent prestigious service lines for the institution.121 Encouraging EMS systems to use prehospital ECGs
as part of protocols that divert patients from community
hospitals to STEMI destination hospitals will be challenging,
because the loss of profitable cardiac patients may impact the
financial viability of a rural, critical access hospital. EMS
providers, emergency physicians, and cardiologists will need
1073
Training and ongoing quality assurance for EMS providers and medical
control physicians
Acquiring prehospital ECG as early as possible during initial scene
evaluation
Minimize scene time when STEMI is diagnosed
Advanced notification of destination hospital
Activation of catheterization laboratory by EMS providers or emergency
physician while patient is en route to hospital
PCI Hospital
Organize reliable wireless networks and technologies
Advanced preparation to receive and evaluate patient
Activation of catheterization laboratory by emergency physician while
patient is en route to hospital
Streamline emergency department evaluation or bypass emergency
department
Prehospital triage for regional hospital networks to bypass non-PCI
hospitals
Research and Quality Assurance
Monitor quality measures, including first medical contact to drug/balloon
Monitor false-positive and false-negative rates
Evaluate whether EMT-basic and EMT-intermediate can acquire
prehospital ECG reliably and efficiently
Promote systematic and routine feedback of performance to all
stakeholders, including EMS, emergency department, and cardiology
EMT indicates emergency medical technician.
to engage and work together to implement an ideal, integrated
prehospital ECG system of care for patients with acute
coronary syndrome.
Additionally, it is unclear what regulatory oversight is
needed to assess quality of prehospital ECG programs. These
issues raise the concern of accountability after their establishment. Much of the daily work required for these systems will
be done at the local healthcare system level, with groups of
expert providers from the community participating in the
design and implementation of these programs. However,
authority and funding for these programs may need to come
from higher levels of government, such as county, state,
or regional health agencies. Increasingly, health agencies
at these regulatory levels are recognizing the importance
of timely therapy for patients with STEMI and categorizing
them similar to trauma patients. This emphasis on rapid
treatment and the expansion of primary PCI to more hospitals
may allow for funding of programs for prehospital ECGs to
be tied in as well.
Summary
Prehospital ECG programs have the potential to improve the
way care is delivered to patients with STEMI in the United
States. Current American Heart Association guidelines recommend that paramedics perform and evaluate a prehospital
ECG routinely on patients with chest pain suspected of
having STEMI (Class IIa, Level of Evidence B).1,3 The central
challenge for healthcare providers is not to simply perform a
1074
Circulation
September 2, 2008
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prehospital ECG, but to use and integrate the diagnostic information from a prehospital ECG with systems of care. The
potential savings in time from first medical contact to reperfusion therapy by integrating prehospital ECGs with hospital
systems of care are considerable and clinically relevant. However, the gaps between use under ideal circumstances and in
routine practice remain substantial (Table 3). There are many
logistic barriers, including the need for increased patient use of
EMS; increased EMS capacity; improved education and quality
assurance for EMS providers; improved collaboration among
EMS, emergency departments, and cardiology; improved organization of hospital systems and providers; and improved coordination of regional hospital networks to provide the ideal
patient care rather than optimize market share. It also is apparent
that several financial barriers, including reimbursement and
cost-effectiveness of this diagnostic technology, will need to be
overcome for prehospital ECGs to gain widespread support
across payors, providers, and healthcare systems. But these
barriers are not insurmountable and can be overcome with
dedicated efforts to improving systems of care. Future investigations and policy measures are needed to encourage EMS,
hospitals, and healthcare systems to adopt and maximize the full
potential of this technology, as well as monitor unintended
consequences.
Many of the barriers to the widespread implementation of
prehospital ECGs are being addressed by the American Heart
Association’s Mission: Lifeline, a national initiative launched
in 2007 to improve systems of care for patients with
STEMI.11 Mission: Lifeline’s initial phase includes Emergency Medical Services System Assessment and Improvement. Working in collaboration with EMS organizations on
national and local levels, Mission: Lifeline is conducting a
comprehensive survey to determine EMS capability, policy,
infrastructure, and resources, including prehospital ECG capability and protocols for care of patients with STEMI. On
the basis of the above assessment, the American Heart
Association plans to build and evaluate the appropriate
infrastructure to ideally serve patients with STEMI that is
tailored at the local, regional, or state level. The implementation phase will address funding, training, the potential for
overuse of STEMI services or procedures, and identification
of underserved populations and development of strategies to
mitigate disparities in access to care, as well as evaluation of
existing process measures and patient outcomes.91
Disclosures
Writing Group Disclosures
Other Research
Support
Speakers’
Bureau/
Honoraria
Ownership
Interest
Consultant/
Advisory Board
Other
Name
Employment
Research Grant
Henry H. Ting
Mayo Clinic
ACC*; Mayo Foundation
for Medical Education
and Research*
None
None
None
None
None
Elizabeth H. Bradley
Yale
University
NHLBI†
None
None
VHA*
None
None
David C. Cone
Yale
University
None
None
None
None
None
None
Jeptha P. Curtis
Yale
University
CO Foundation for
Medical Care*
None
None
None
None
None
Barbara J. Drew
UCSF
None
Medtronic Emergency
Response Systems*
GE Healthcare*;
Phillips Medical*
None
GE Healthcare*
None
Penn State
University
None
None
None
None
Senior Science
Editor,
AHA-ECC†
None
UCLA
None
None
None
None
None
None
W. Brian Gibler
University of
Cincinnati
Abbott/iSTAT⫹O7†
None
None
Audicor*;
Siloam*
None
Educational grant
support from
Abbott†; Biosite†;
Bristol-Myers
Squibb†; Daiichi
Sankyo Lilly†;
Otsuka†;
Sanofi-Aventis†;
ScheringPlough†; The
Medicines
Company†
David C. Goff
Wake Forest
University
None
None
None
None
None
None
John M. Field
William J. French
(Continued)
Ting et al
Prehospital ECGs for Acute Coronary Syndrome
1075
Continued
Employment
Research Grant
Other Research
Support
Speakers’
Bureau/Honoraria
Ownership
Interest
Consultant/
Advisory Board
Other
Alice K. Jacobs
Boston Medical
Center
None
None
None
None
None
None
Harlan M. Krumholz
Yale University
None
None
None
None
None
None
University of
Michigan
AHRQ†
None
None
None
None
None
Robert E. O’Connor
University of
Virginia Health
System
None
None
None
None
None
None
Jeremiah D. Schuur
VAMC and Yale
University
None
None
None
None
None
None
Name
Brahmajee K.
Nallamothu
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This table represents the relationships of writing group members that may be perceived as actual or reasonably perceived conflicts of interest as reported on the
Disclosure Questionnaire, which all members of the writing group are required to complete and submit. A relationship is considered to be “significant” if (a) the person
receives $10 000 or more during any 12-month period, or 5% or more of the person’s gross income; or (b) the person owns 5% or more of the voting stock or share
of the entity, or owns $10 000 or more of the fair market value of the entity. A relationship is considered to be “modest” if it is less than “significant” under the
preceding definition.
*Modest.
†Significant.
Reviewer Disclosures
Reviewer
Employment
Research
Grant
Other Research
Support
Speakers’
Bureau/Honoraria
Expert
Witness
Ownership
Interest
Consultant/Advisory
Board
Other
Elliott M. Antman
Brigham and Women’s
Hospital
None
None
None
None
None
None
None
Eric Bates
University of Michigan
None
None
None
None
None
None
None
James V.
Dunford
University of California,
San Diego
None
None
None
None
None
None
None
This table represents the relationship of reviewers that may be perceived as actual or reasonably perceived conflicts of interest as reported on the Disclosure
Questionnaire, which all reviewers are required to complete and submit.
References
1. Antman EM, Anbe DT, Armstrong PW, Bates ER, Green LA, Hand M,
Hochman JS, Krumholz HM, Kushner FG, Lamas GA, Mullany CJ,
Ornato JP, Pearle DL, Sloan MA, Smith SC Jr, Alpert JS, Anderson JL,
Faxon DP, Fuster V, Gibbons RJ, Gregoratos G, Halperin JL, Hiratzka
LF, Hunt SA, Jacobs AK. ACC/AHA guidelines for the management of
patients with ST-elevation myocardial infarction– executive summary: a
report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise
the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction). Circulation. 2004;110:588 – 636.
2. ECC Committee, Subcommittees and Task Forces of the American
Heart Association. 2005 American Heart Association Guidelines for
Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
Circulation. 2005;112(suppl IV):IV-1–IV-203.
3. Antman EM, Hand M, Armstrong PW, Bates ER, Green LA,
Halasyamani LK, Hochman JS, Krumholz HM, Lamas GA, Mullany CJ,
Pearle DL, Sloan MA, Smith SC Jr; 2004 Writing Committee Members,
Anbe DT, Kushner FG, Ornato JP, Jacobs AK, Adams CD, Anderson
JL, Buller CE, Creager MA, Ettinger SM, Halperin JL, Hunt SA, Lytle
BW, Nishimura R, Page RL, Riegel B, Tarkington LG, Yancy CW. 2007
Focused Update of the ACC/AHA 2004 Guidelines for the Management
of Patients With ST-Elevation Myocardial Infarction: a report of the
American College of Cardiology/American Heart Association Task
Force on Practice Guidelines: developed in collaboration with the
Canadian Cardiovascular Society, endorsed by the American Academy
of Family Physicians: 2007 Writing Group to Review New Evidence
and Update the ACC/AHA 2004 Guidelines for the Management of
Patients With ST-Elevation Myocardial Infarction, Writing on Behalf of
the 2004 Writing Committee. Circulation. 2008;117:296 –329.
4. Emergency department: rapid identification and treatment of patients
with acute myocardial infarction: National Heart Attack Alert Program
5.
6.
7.
8.
9.
10.
11.
Coordinating Committee, 60 Minutes to Treatment Working Group. Ann
Emerg Med. 1994;23:311–329.
Dracup K, Alonzo AA, Atkins JM, Bennett NM, Braslow A, Clark LT,
Eisenberg M, Ferdinand KC, Frye R, Green L, Hill MN, Kennedy JW,
Kline-Rogers E, Moser DK, Ornato JP, Pitt B, Scott JD, Selker HP,
Silva SJ, Thies W, Weaver WD, Wenger NK, White SK. The physician’s role in minimizing prehospital delay in patients at high
Implementation and Integration of Prehospital ECGs Into
Systems of Care for Acute Coronary Syndrome
A Scientific Statement From the American Heart Association
Interdisciplinary Council on Quality of Care and Outcomes Research,
Emergency Cardiovascular Care Committee, Council on Cardiovascular
Nursing, and Council on Clinical Cardiology
Henry H. Ting, MD, MBA, Chair; Harlan M. Krumholz, MD, SM, FAHA, Co-Chair;
Elizabeth H. Bradley, PhD; David C. Cone, MD; Jeptha P. Curtis, MD;
Barbara J. Drew, RN, PhD, FAHA; John M. Field, MD; William J. French, MD;
W. Brian Gibler, MD; David C. Goff, MD, PhD, FAHA; Alice K. Jacobs, MD, FAHA;
Brahmajee K. Nallamothu, MD, MPH; Robert E. O’Connor, MD; Jeremiah D. Schuur, MD, MHS
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C
linical case: A 58-year-old woman called 9-1-1 with
acute onset of chest pain that had persisted for 30
minutes. She had a history of hypertension, hyperlipidemia, and type 2 diabetes mellitus but no previous history
of myocardial infarction or heart failure. Her medications
included aspirin, atorvastatin, lisinopril, and metoprolol.
Paramedics were dispatched, and a prehospital ECG demonstrated 3- to 4-mm ST-segment elevation in leads I,
aVL, and V2 through V6 (Figure 1). Her examination
revealed a regular pulse of 90 bpm, a blood pressure of
100/60 mm Hg, clear lungs, and normal heart sounds with
no murmurs. Paramedics interpreted the prehospital ECG
and activated the catheterization laboratory en route to the
hospital. On hospital arrival, the patient was transported
directly to the catheterization laboratory. Coronary angiography demonstrated an occluded proximal left anterior
descending artery, which was successfully treated with
balloon angioplasty and a stent. The pertinent time intervals were as follows: paramedic dispatch to balloon time,
56 minutes; paramedic arrival at the scene to balloon time,
46 minutes; hospital door to balloon time, 23 minutes. Her
biomarkers revealed a peak troponin T of 2.42 ng/mL and a peak
creatine kinase muscle-brain isoenzyme of 26.8 ng/mL. An
echocardiogram demonstrated normal left ventricular ejection
fraction of 55%, with mild anterior hypokinesis, and the patient
was discharged on hospital day 3.
Current Guidelines for Prehospital ECGs
Among Patients With ST-Segment–Elevation
Myocardial Infarction
American Heart Association national guidelines,1–3 as well as
other consensus and scientific statements,4 –11 recommend
that emergency medical services (EMS) acquire and use
prehospital ECGs to evaluate patients with suspected acute
coronary syndrome. Despite these recommendations, prehospital ECGs are used in fewer than 10% of patients with
ST-segment– elevation myocardial infarction (STEMI),12,13
and this rate has not substantially changed since the mid1990s. Furthermore, even when a prehospital ECG is acquired, the information is often not effectively translated into
action and coordinated with hospital systems of care to
decrease delays in reperfusion therapy.13 The purpose of this
article is to summarize evidence concerning the benefits of
using prehospital ECGs, review barriers and challenges to
routine use, and recommend approaches to enhance their
effectiveness for improving quality of care for patients with
acute coronary syndromes.
The American Heart Association makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside
relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required
to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest.
This statement was approved by the American Heart Association Science Advisory and Coordinating Committee on July 2, 2008. A single reprint is
available by calling 800-242-8721 (US only) or by writing the American Heart Association, Public Information, 7272 Greenville Ave, Dallas, TX
75231-4596. Ask for reprint No. 71-0454. A copy of the statement is also available at http://www.americanheart.org/presenter.jhtml?identifier⫽3003999
by selecting either the “topic list” link or the “chronological list” link. To purchase additional reprints, call 843-216-2533 or e-mail
kelle.ramsay@wolterskluwer.com.
Expert peer review of AHA Scientific Statements is conducted at the AHA National Center. For more on AHA statements and guidelines development,
visit http://www.americanheart.org/presenter.jhtml?identifier⫽3023366.
Permissions: Multiple copies, modification, alteration, enhancement, and/or distribution of this document are not permitted without the express
permission of the American Heart Association. Instructions for obtaining permission are located at http://www.americanheart.org/presenter.jhtml?
identifier⫽4431. A link to the “Permission Request Form” appears on the right side of the page.
(Circulation. 2008;118:1066-1079.)
© 2008 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.108.190402
1066
Ting et al
Prehospital ECGs for Acute Coronary Syndrome
1067
Figure 1. Prehospital ECG.
What Are the Benefits of Using Prehospital
ECGs in Patients With STEMI?
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Multiple studies have demonstrated the benefits of prehospital ECGs for decreasing door-to-drug time and door-toballoon time in patients with STEMI.12–30 The direction and
magnitude of the time savings are clinically relevant, resulting in an approximately 10-minute decrease in door-to-drug
time and 15- to 20-minute decrease in door-to-balloon
time.12,13 However, these time savings may not reflect the full
potential of prehospital ECGs to decrease delays in reperfusion therapy. In fact, studies have shown further reductions in
door-to-balloon time when prehospital ECGs are used to
activate the catheterization laboratory while the patient is en
route to the hospital.31–37
For patients transported by EMS without prehospital ECG,
delay from symptom onset to reperfusion therapy, which
reflects the overall period of ischemic injury, can be divided
into 4 time intervals: (1) symptom onset to EMS arrival, (2)
EMS arrival to hospital arrival, (3) hospital arrival to ECG,
and (4) ECG to reperfusion. Prehospital ECG programs, if
effectively implemented and coordinated with hospital systems of care, would be expected to decrease the latter 3 time
intervals (Figure 2). The second interval is composed of time
from first medical contact by EMS to hospital door, and EMS
personnel may behave with more urgency if a diagnosis of
STEMI has been made in the field. The third interval is
essentially eliminated with a prehospital ECG. The fourth
interval can be decreased by advanced notification of the
hospital to receive and evaluate the patient, to activate the
catheterization laboratory while the patient is en route, or to
bypass the emergency department and transport the patient
directly to the catheterization laboratory. Scholz and colleagues reported the impact of prehospital ECGs on these
time intervals from 114 patients with STEMI treated within
an integrated system of care.38 The system consisted of
acquiring a prehospital ECG by emergency responders (in
Germany, this was generally a physician), transmitting the
prehospital ECG to a fax machine at the percutaneous
coronary intervention (PCI) hospital cardiac intensive care
unit, activating the catheterization laboratory en route if
STEMI was diagnosed, and bypassing the emergency department when the catheterization laboratory team was on-site.
Pertinent time intervals were collected for 1 year. Comparing
performance in the last quarter of implementing this system
with the first quarter (reference group), the time spent at the
scene decreased from 25 to 19 minutes, time spent in the
Reperfusion goals: EMSEMS-toto-drug < 30 min; EMSEMS-toto-balloon < 90 min; Symptom
onsetonset-toto-reperfusion < 120 min (text adapted from reference 1)
(1) PH ECG interpreted by EMS or transmitted by cell phone to hospital
(2) Pre-arrival activation of catheterization lab
Onset of
Symptoms
EMS Arrival
Prehospital
Electrocardiogram
Hospital
Arrival
Reperfusion
Increasing loss of myocytes
Figure 2. Reperfusion time goals for patients with ST-segment– elevation myocardial infarction.
1068
Circulation
‘Table 1.
September 2, 2008
Models for interpreting Prehospital ECGs
Method of Interpreting Prehospital
ECG
Pros
Cons
Computer algorithm interpretation
Rapid, easy
No wireless network or technology
requirements
False-positive and false-negative rates higher than
physician interpretation
Paramedic interpretation
Rapid, easy
No wireless network or technology
requirements
Requires intensive education and quality
assurance program
More complex in communities with multiple EMS
providers and agencies
Wireless transmission and physician
interpretation
Theoretically, lowest rate of false-positives and
false-negatives
Medical oversight can provide guidance on
destination hospital and treatment en route
New technology requirement for EMS providers
and hospital
Reliable wireless network Transmission unit on
ambulance
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Receiver station unit at hospital
Smartphones for physicians
Requires system to ensure immediate
interpretation by physician
Transmission failures
EMS indicates emergency medical services.
emergency department decreased from 14 to 3 minutes, time
from arterial access to balloon decreased from 21 to 11
minutes, door-to-balloon time decreased from 54 to 26
minutes, and first medical contact to balloon time decreased
from 113 to 74 minutes. The authors also concluded that
systematic, quarterly feedback on performance to cardiology,
emergency department, and EMS stakeholders was an important component in improving prehospital and hospital processes of care.38
Can EMS Providers Acquire
Prehospital ECGs?
A survey found that 90% of EMS systems serving the 200
largest cities in the United States had 12-lead ECG equipment
available in their ambulance systems.39 EMS providers can
rapidly acquire diagnostic-quality prehospital ECGs with an
average increase of 5 to 6 minutes in the on-scene time
interval.14 –16,28,40 – 49 To acquire diagnostic-quality prehospital
ECGs, a valuable strategy is to educate EMS providers about
the importance of careful patient positioning and lead placement. Movement artifact, lead misplacement, and poor skin
contact can result in poor-quality tracing that can be misinterpreted by algorithms or EMS providers.
One study, which used data from the National Registry of
Myocardial Infarction between 1994 and 1996, found that
patients with prehospital ECGs had time intervals that were
20 minutes longer from symptom onset to hospital arrival.12
This finding was difficult to interpret, however, as there was
no measure of how long the prehospital ECG required and
potential selection bias in who received a prehospital ECG.
For example, patients who had a longer transport distance
may have received a higher rate of prehospital ECGs as
compared with those with a shorter transport distance. An
analysis of the National Registry of Myocardial Infarction
between 2000 and 2002 found that patients with prehospital
ECGs did not have longer times from symptom onset to
hospital arrival.13
Can EMS Providers Reliably Interpret or
Communicate Prehospital ECGs?
Several studies have examined the feasibility of EMS providers identifying STEMI using prehospital ECGs with or
without wireless transmission.20,36,50 –58 The pros and cons for
computer algorithm interpretation, paramedic interpretation,
and wireless transmission for physician interpretation of
prehospital ECGs are summarized in Table 1. There are no
data to compare the effectiveness of these different approaches for diagnostic accuracy or quality of reperfusion
therapy delivered to patients with STEMI. The choice of
which option to use may also be limited by the specific
resources available in the community or its local geography.
Studies have also shown that paramedics with specific
ECG training can reliably interpret prehospital ECGs without
transmitting to a hospital or physician. Trained paramedics
can identify STEMI with sensitivity ranging from 71% to
97% and specificity ranging from 91% to 100%,15,16,59 – 65 and
with good agreement between paramedics and emergency
department physicians ( ranging from 0.59 to 0.73).20,60,64
The sensitivity (97%) and specificity (91%) of trained paramedics to interpret prehospital ECGs and diagnose STEMI
was particularly high in one study, which included a 2-day
training seminar.62 A study of this issue, conducted in the
United States with 151 patients with suspected acute myocardial infarction transported by a large urban EMS system,
found that trained paramedics had 80% sensitivity and 97%
specificity in diagnosing STEMI with prehospital ECGs, with
good agreement between paramedics and emergency physicians (⫽0.73).64
Ting et al
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Alternatively, prehospital ECGs can be transmitted by
EMS for physician interpretation to drive decision making,
but this approach has been limited by technology requirements for rapid and reliable transmission of prehospital
ECGs. Two pilot studies have demonstrated that wireless
transmission of prehospital ECG is feasible.36,55 In the Timely
Intervention in Myocardial Emergency–Northeast Experience
(TIME-NE) conducted in Concord, NC, 24 patients with
STEMI had successful wireless transmission of prehospital
ECGs to a hospital receiving station and the on-call cardiologist’s smartphone.55 The on-call cardiologist then decided
whether to activate the catheterization laboratory on the basis
of the prehospital ECG. Median door-to-balloon time decreased in this study to 50 minutes as compared with 101
minutes for historical controls; however, there were 19
patients with STEMI who experienced failed wireless transmission. In the ST-Segment Analysis Using Wireless Technology in Acute Myocardial Infarction (STAT-MI) study
conducted in Newark, NJ, 80 patients had prehospital ECGs
transmitted using a wireless cellular phone network to a
secure hospital central server and to the on-call cardiologist’s
smartphone.36 This model had no transmission failures; median time from prehospital ECG acquisition to availability on
the remote server was 2 minutes and on the smartphone was
4 minutes. The door-to-balloon time was 80 minutes with use
of prehospital ECGs, as compared with 146 minutes for
historical controls without use of prehospital ECGs. In
geographic regions with reliable wireless network coverage,
wireless transmission of prehospital ECG for physician interpretation is feasible and reliable; however, current wireless
networks can fail to transmit or encounter significant delays
in up to 20% to 44% of cases as a result of wireless “dead
Prehospital ECGs for Acute Coronary Syndrome
1069
zones” in a moving ambulance or in rural areas with sparse
coverage.50,55,62,66,67
Wireless transmission prehospital ECG systems are commercially available from Medtronic36,57 (Minneapolis, Minn),
Welch Allyn55 (Beaverton, Ore), Zoll Medical30 (Chelmsford,
Mass), and Phillips Healthcare (Andover, Mass). These
systems acquire the prehospital ECG and automatically transmit the data using Bluetooth protocol to a nearby cellular
phone. The cellular phone functions as a router to transmit the
data to a central receiving station and smartphones via a
wireless cellular network or wireless local area network
(IEEE 802.11).68 –71 A novel approach using camera phones
with multimedia messaging service has been proposed and
tested in 10 patients.72 A camera phone obtains a digital
picture of the prehospital ECG paper printout and wirelessly
transmits the picture to an e-mail account, and the ECG image
can be viewed on any multimedia messaging service– capable
device, such as a computer or smartphone. This approach
may be a simple, low-cost, and innovative technology73 to
communicate diagnostic image data and warrants further
study for feasibility in real-world practices.
Can EMS and Hospitals Organize Systems to
Effectively Use Prehospital ECGs?
EMS and hospitals should organize efficient systems of care
for patients with STEMI from the prehospital phase of care to
hospital arrival and reperfusion therapy in the hospital phase
of care. The typical current process2 for emergency cardiac
care initiated by a 9-1-1 call is contrasted with the ideal
process in Figure 3. Historically, EMS providers have been
trained to follow these steps in evaluating patients with chest
pain in the field: (1) assess airway, breathing, circulation, and
Figure 3. Current versus ideal processes to integrate prehospital ECGs into systems of care.
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vital signs; (2) obtain focused history and examination; (3)
assess cardiac rhythm; (4) initiate treatment with oxygen,
aspirin, nitroglycerin, and morphine and insert intravenous
line; (5) recommended: acquire 12-lead prehospital ECG at
the scene, after the patient is transferred to the ambulance, or
while en route to the hospital. Because the 12-lead ECG
represents the critical data for diagnosis and decision making
in patients with chest pain, it should be prioritized and
performed as early as possible at the scene. If a STEMI is
identified on the prehospital ECG, then scene times should be
minimized, with expedited transport to the hospital. Moreover, if the prehospital ECG is communicated to the destination hospital shortly after first medical contact with EMS
providers, then the hospital will have more time to prepare for
the patient.
The information from a prehospital ECG and advanced
notification should lead to efficient action by hospital systems
of care to deliver prompt reperfusion therapy, including
preparing to receive and evaluate the patient, activating the
catheterization laboratory while the patient is en route, or
bypassing the emergency department and transporting the
patient directly to the catheterization laboratory.32,37,74 If
patients are evaluated in the emergency department, the
evaluation should be streamlined by having a physician
and necessary resources (eg, translators, nurses) ready
before patient arrival, following a standard protocol for
treatment, and minimizing physical movement, such as
transferring between stretchers. Although bypassing the
emergency department may be intuitively faster, concerns
have been raised about processes for obtaining informed
consent, patient safety, and consideration of alternative
diagnoses (eg, aortic dissection, intracranial hemorrhage)
or other false-positives that may account for the STsegment elevation on the ECG in up to 10% to 15% of
patients.75–77 Furthermore, during off hours,78,79 the catheterization team may not have arrived at the hospital
before the ambulance, and the patient will need to be
observed in a critical care setting until the catheterization
laboratory is ready to receive the patient.
Table 2.
Can Regional Networks of Hospitals Organize
Systems to Effectively Use Prehospital ECGs?
Patients with STEMI who require interhospital transfer experience substantial delays with a median first hospital
door-to-balloon time of 180 minutes.80 In the United States,
regional networks of hospitals and systems of care have been
implemented and evaluated to improve time to reperfusion
therapy for patients who initially present to a community
hospital without on-site PCI capability.35,81– 83 Similar, but
broader systems of optimizing reperfusion therapy across
populations have also been in place in Europe for several
years.24,84,85 European systems often have a physician in the
ambulance, a central dispatch center for ambulances, and
highly organized regional prehospital care, which stands in
contrast to the disorganized, competitive environment in the
United States.
Prehospital ECGs can play an important role for triage of
patients in a regional network of hospitals, and the two
models proposed include prehospital triage versus interhospital transfer.3,11,74,86 – 89 The prehospital triage model transports patients with STEMI to the closest PCI center and
bypasses hospitals without PCI capability. The interhospital
transfer model focuses on advanced notification and efficient
transfer of patients from non-PCI hospitals to PCI centers.11
Several key factors, including distance, urban versus rural
location, collaborative versus competitive relationships between hospitals, and variability of EMS providers, influence
which model is best suited for specific regional populations.
An analysis of the US Census Survey and the American
Hospital Association Annual Survey showed that 80% of the
adult population live within 60 minutes of a PCI-capable
hospital, and only 5% live farther than 90 minutes from one.90
However, there are still 20% of the adult population and large
geographic areas that do not meet this standard. One model of
regionalized STEMI care does not preclude the other. Both
can coexist within a single network and are often driven by
specific resources available within a community and local
geography. No data comparing the models exist, and potential
unintended consequences, such as exceptionally long delays
to reperfusion, should be monitored.10,91
Comparison of Existing Prehospital ECG Programs
Location
Prehospital ECG Interpretation
Activate Catheterization Lab en Route to
Hospital
Bypass Non-PCI
Hospitals
Boston64,92
Paramedic interpretation
Yes (activation by emergency department
physician based on paramedic
interpretation)
Yes (for all patients with
“definite STEMI” or
“possible STEMI”)
Los Angeles County76,87
Computer algorithm interpretation
Yes (activation by emergency department
physician based on computer
algorithm interpretation)
Yes (for all patients with
acute MI)
North Carolina83
Mixed (used computer algorithm interpretation,
paramedic interpretation, or wireless
transmission)
Mixed (activation by paramedics or
emergency department physician)
Mixed (paramedics
occasionally diverted
patients with STEMI
to nearest PCI
hospital)
Ottawa65,96
Paramedic interpretation
Yes (activation by paramedic through a
central page operator)
Yes (for all patients with
STEMI)
PCI indicates percutaneous coronary intervention; MI, myocardial infarction; and STEMI, ST-segment– elevation myocardial infarction.
Ting et al
How Have Prehospital ECGs Been
Incorporated Into Existing Systems of Care?
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Many communities are implementing prehospital ECG programs that are in varying stages of development, and Boston,
Los Angeles, North Carolina, and Ottawa (Canada) provide
important contrasts (Table 2). The Boston EMS program, one
of the country’s first, involves municipal paramedics trained
to interpret and categorize prehospital ECGs as definite
STEMI, possible STEMI, or nondiagnostic.9,64,92 Patients
with definite STEMI or possible STEMI are triaged to the
closest PCI hospital, and the former are brought directly to
the catheterization laboratory and the latter are evaluated
in the emergency department. The emergency physician
decides whether to activate the catheterization laboratory
on the basis of the paramedic interpretation while the
patient is en route to the hospital. The Boston EMS
program covers a relatively small geographic area (⬍50
square miles) with 60 to 70 municipal paramedics, and
private EMS providers do not participate in the program.
In contrast, the Los Angeles County EMS program includes all EMS providers, an area of ⬎4000 square miles
with approximately 2500 paramedics working for 27 agencies.76,87 The variability and sheer numbers of EMS providers
to train in ECG interpretation were considered an insurmountable obstacle. The Los Angeles County EMS program
therefore relies on computer algorithm interpretation that
identifies ***ACUTE MI*** to prompt EMS transport of
patients to the closest PCI center (or STEMI receiving
center). The emergency physician decides whether to activate
the catheterization laboratory on the basis of the computer
algorithm interpretation while the patient is en route to the
hospital. A few hospitals in Los Angeles County have started
to pilot the feasibility of transmitting prehospital ECGs for
physician interpretation. Both the Boston and Los Angeles
programs are undergoing formal evaluation. There are also
ongoing clinical trials in other parts of the United States
evaluating the effectiveness of prehospital ECGs to decrease
first medical contact to balloon/drug times.93–95
The Reperfusion of Acute Myocardial Infarction in North
Carolina Emergency Departments (RACE) Investigators implemented a statewide approach to improve timeliness of
reperfusion therapy for patients with STEMI.83 The use of
prehospital ECGs was high, and prehospital ECGs were
acquired in 61% and 43% of patients with STEMI transported
by EMS to PCI hospitals and non-PCI hospitals, respectively.
However, the RACE program did not have standardized
procedures for when to acquire a prehospital ECG, who
would interpret the prehospital ECG, and how to integrate the
prehospital ECG with systems of care. Each hospital and
region decided how to interpret and integrate the prehospital
ECG based on available resources, geography, and decisions
by regional leadership.
The Ottawa citywide system, which included 1 PCI
center and 4 non-PCI hospitals located within 7 miles of
the PCI center, reported their 1-year experience in 344
patients with STEMI.96 The first hospital door-to-balloon
time was 69 minutes when paramedics acquired and
interpreted a prehospital ECG and bypassed non-PCI
hospitals as compared with 123 minutes when a prehospi-
Prehospital ECGs for Acute Coronary Syndrome
1071
tal ECG was not performed and the patient was initially
brought to a non-PCI hospital and required interhospital
transfer for primary PCI.
What Are the Barriers to Implementing
Successful Prehospital ECG Programs?
What Are the Costs and Benefits for Prehospital
ECG Programs?
Currently, there are no cost-effectiveness models to evaluate
this diagnostic technology from the different perspectives of
patients, hospitals, payors, and society.97 One study reported
that the incremental cost to upgrade prehospital ECG equipment to wireless capability was $16 100, which consisted of
$11 000 for a receiving station, $600 for cell phones, and
$4500 for data cables.57 The direct cost for prehospital ECG
equipment with monitoring and defibrillation capability
ranges from $9000 to $25 000, but this does not take into
account other direct and indirect costs for training, quality
assurance, and organizing complex EMS and hospital systems.8,98 Developing and implementing STEMI systems require substantial investment of resources that impact on the
value of acquiring and using the information provided by
prehospital ECGs. Comparative cost models for efficiently
acquiring, interpreting, and transmitting prehospital ECGs
within the context of STEMI systems will be informative and
valuable. Additionally, it will be important to compare the
development of STEMI systems of care with other healthcare
priorities, both in cardiovascular medicine and other
disciplines.
What Training and Maintenance of Competency
Do EMS Providers Need?
In the United States, EMS providers are trained to several
competency levels. Although the federal government (http://
www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.2a0771e91
315babbbf30811060008a0c/) has defined a standard curricula
for each of 4 levels (first responder, emergency medical technician [EMT]– basic, EMT-intermediate, and EMT-paramedic),99
many states use definitions and regulations that vary significantly between states as well as within a single state (rural versus
urban areas). The National Registry of EMTs (www.nremt.org),
the nation’s de facto “board” for certification, currently certifies
EMS personnel at the first responder, EMT-basic, EMTintermediate/1985, EMT-intermediate/1999, and EMTparamedic levels.
First responder roles are often provided by firefighters or law
enforcement officers.9 EMT-basic personnel provide basic life
support, including first aid, cardiopulmonary resuscitation, oxygen, and early defibrillation. EMT-intermediate and EMTparamedic personnel provide advanced life support, including
intubation and intravenous medications. Prehospital ECG acquisition has historically been limited to EMT-paramedic. The
current EMT-paramedic national standard curriculum99 includes
the following objectives intended to provide paramedics with a
basic understanding of the pathophysiology and ECG features of
acute myocardial infarction:
5–2.9 Identify the arterial blood supply to any given area of
the myocardium.
1072
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September 2, 2008
5–2.22 Discuss the pathophysiology of cardiac disease and
injury.
5–2.34 Relate the cardiac surfaces or areas represented by the
ECG leads.
5–2.48 Recognize the changes on the ECG that may reflect
evidence of myocardial ischemia and injury.
5–2.78 Identify the ECG changes characteristically seen
during evolution of an acute myocardial infarction.
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The National Association of EMS Educators (www.naemse.
org) is presently revising all of the existing national standard
curricula for EMS with new standards. The initial draft of this
document, released in June 2007, includes 12-lead ECG
interpretation as a required competency for paramedics.
Currently, no standards exist regarding how much initial
and subsequent periodic education is required to achieve
and maintain competency in prehospital ECG interpretation. Also, there are no standard protocols for when and
what patient subsets to obtain a prehospital ECG, as well
as what to do with the data.
It has been proposed that prehospital ECG acquisition be
extended to EMT-basic and EMT-intermediate levels.9 A
preliminary study showed that EMT-basic personnel could
acquire, but not interpret, ECGs in a comparable amount of
time as compared with EMT-paramedics.100 Although rural
geographic areas without paramedic coverage could benefit
by extending prehospital ECG acquisition skills to EMTbasic personnel, this would require significant changes in
current curriculum, training, protocols, and policy.
EMS systems vary substantially with regard to configuration and structure, each using some combination of EMS
providers to deliver emergency medical care for rural, suburban, or urban communities. Physician oversight also varies,
with only a small number of large EMS systems having
full-time physician medical directors. Given the challenges
with EMS training, maintenance of competency,101–103 quality management, and medical oversight, there is no “one size
fits all” or even “one size fits most” solution.
How Will Patients With Acute Coronary
Syndromes Use EMS?
The reluctance of patients with acute coronary syndromes
to call 9-1-1 is a major obstacle to realization of the full
public health benefits of prehospital ECGs and organizing
systems of care. Prior studies have shown that 10% to 59%
of patients with chest pain use EMS104 –111 and less than
half of patients with STEMI use EMS versus self-transport
to the hospital.8,110 Studies have demonstrated that patients
with STEMI arriving by ambulance receive faster reperfusion therapy than those who arrive by self-transport,
particularly in busy, overcrowded emergency departments.112,113 Unfortunately, educational and media efforts
to increase EMS use have had limited success.114 Conversely, if substantially more patients with chest pain call
9-1-1, EMS and emergency department systems may need
to grow to provide adequate access and capacity.113,115–117
Efforts to increase the reach of prehospital ECG programs
will need to address the limited use of EMS by patients
with STEMI and the need to expand EMS capacity to meet
increased demand.
What Areas of Future Research Need
to Be Addressed?
How Will the Use of Prehospital ECGs Be
Measured and Assessed?
For the most part, current measures for assessing the use and
timeliness of reperfusion therapy in STEMI (eg, door-toballoon time) are hospital-based and therefore inadequate for
evaluating the effectiveness of prehospital ECGs. To evaluate
the incremental benefit of this technology, current hospitalbased measures (door-to-balloon time) would need to evolve
to patient-centered measures, such as first medical contact to
reperfusion or symptom onset to reperfusion. Current STEMI
guidelines recommend that the pertinent metric for quality of
reperfusion therapy are first medical contact to balloon ⬍90
minutes and first medical contact to drug ⬍30 minutes.3
Furthermore, we need to assess patient responsiveness after
onset of symptoms, appropriate use of EMS and EMS
responsiveness, EMS scene time to acquire prehospital
ECGs, and effective communication of this data to destination hospitals and its use in decision making about reperfusion therapy. There needs to be careful analysis of the
denominator or eligible population who should have received
a prehospital ECG versus those who actually received a
prehospital ECG. For providers to adopt the technology, an
improved understanding of how potential gains in rapid
reperfusion translate into improved clinical outcomes would
be ideal, as well as an understanding of the frequency of false
alarms and other unintended consequences. Real-world examples are particularly helpful in this regard, given the
wide-ranging approaches that different types of healthcare
systems—for example, urban versus rural—may require.
These examples would also be important for assessing the
overall value of this technology relative to the financial
investment in equipment, training, and organizing STEMI
systems.
How Will Prehospital ECGs Be Performed and in
Whom Should They Be Used?
There remains a poor understanding of who will acquire and
interpret prehospital ECGs and in whom these tests should be
performed. A direct comparison of diagnostic accuracy and
times for ECG interpretation by computer algorithm, paramedics, and emergency physicians or cardiologists would be
valuable. Most regions that use prehospital ECGs have
standard protocols for what types of symptoms should prompt
acquisition of the test, but the false-positive and falsenegative rates have been poorly characterized in general. It
would be valuable to understand the frequency of STsegment elevation from other causes,118 such as early repolarization, left ventricular hypertrophy, left bundle-branch
block, pericarditis, hyperkalemia, atrial flutter, Brugada syndrome, pulmonary embolism, and Prinzmetal angina, as
prehospital ECG programs are implemented.
It has been reported that approximately 5% of patients
with chest pain who are evaluated by EMS have
STEMI.59,76 The incremental value of this technology
when the number needed to treat is 20 for 1 patient who
benefits needs to be verified and elucidated in patients with
Ting et al
Prehospital ECGs for Acute Coronary Syndrome
more atypical symptoms, such as shortness of breath,
dizziness, or other atypical symptoms.
Table 3. Requirements for an Integrated Prehospital ECG
System of Care
How Will Prehospital ECGs Be Integrated Into
Practice Without Unintended Consequences?
EMS
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An important area of investigation is how the prehospital
ECGs can optimize decision making to triage patients to
destination hospitals with and without PCI capability. The
broad and diverse population of the United States poses
several challenges to establishing effective systems of care
for incorporating prehospital ECGs into routine clinical
practice. It is apparent that a one-size-fits-all approach is
neither practical nor ideal. The use of this technology
requires a careful assessment of the local needs and
resources within each community, with the overarching
goal to improve patient care and access, timeliness of
reperfusion therapy, and the proportion of eligible patients
who receive reperfusion.
A better understanding of the precise role of different
providers in the design of systems that use prehospital ECGs
is needed. How will the roles of EMS and emergency
physicians evolve for activating the catheterization laboratory? How will safeguards be established so that patients with
other life-threatening conditions that may mimic or complicate STEMI are not missed and care is not delayed? Investigators should be encouraged to explore both the benefits and
pitfalls of implementing a prehospital ECG program. There
may be unintended deleterious effects to patients, such as
longer scene times and overall longer time from symptom
onset to reperfusion.
What Policy Measures Should Be Adopted to
Encourage Use of Prehospital ECGs?
The healthcare system within the United States is not currently
organized in a way that encourages the adoption of prehospital
ECGs or regional systems of care for STEMI.90,119,120 Numerous
providers in the prehospital and hospital settings make it challenging to foster cooperation. For example, in many regions,
there are several private, for-profit EMS that are responsible
for evaluating and transporting patients. Successful implementation will require the inclusion of these providers and
may necessitate that prehospital ECGs are required by
regulation and are reimbursed. Currently, EMS reimbursement is typically based on 2 levels of care as well as
distances traveled, but EMS is not reimbursed for specific
services delivered, including a prehospital ECG. However,
it also is unclear whether expansion of reimbursement for
prehospital ECGs may lead to overuse and misuse.
Issues surrounding reimbursement are also fundamental to
hospitals. Cardiac patients are seen as lucrative, given the
high rate of invasive procedures associated with these conditions, and represent prestigious service lines for the institution.121 Encouraging EMS systems to use prehospital ECGs
as part of protocols that divert patients from community
hospitals to STEMI destination hospitals will be challenging,
because the loss of profitable cardiac patients may impact the
financial viability of a rural, critical access hospital. EMS
providers, emergency physicians, and cardiologists will need
1073
Training and ongoing quality assurance for EMS providers and medical
control physicians
Acquiring prehospital ECG as early as possible during initial scene
evaluation
Minimize scene time when STEMI is diagnosed
Advanced notification of destination hospital
Activation of catheterization laboratory by EMS providers or emergency
physician while patient is en route to hospital
PCI Hospital
Organize reliable wireless networks and technologies
Advanced preparation to receive and evaluate patient
Activation of catheterization laboratory by emergency physician while
patient is en route to hospital
Streamline emergency department evaluation or bypass emergency
department
Prehospital triage for regional hospital networks to bypass non-PCI
hospitals
Research and Quality Assurance
Monitor quality measures, including first medical contact to drug/balloon
Monitor false-positive and false-negative rates
Evaluate whether EMT-basic and EMT-intermediate can acquire
prehospital ECG reliably and efficiently
Promote systematic and routine feedback of performance to all
stakeholders, including EMS, emergency department, and cardiology
EMT indicates emergency medical technician.
to engage and work together to implement an ideal, integrated
prehospital ECG system of care for patients with acute
coronary syndrome.
Additionally, it is unclear what regulatory oversight is
needed to assess quality of prehospital ECG programs. These
issues raise the concern of accountability after their establishment. Much of the daily work required for these systems will
be done at the local healthcare system level, with groups of
expert providers from the community participating in the
design and implementation of these programs. However,
authority and funding for these programs may need to come
from higher levels of government, such as county, state,
or regional health agencies. Increasingly, health agencies
at these regulatory levels are recognizing the importance
of timely therapy for patients with STEMI and categorizing
them similar to trauma patients. This emphasis on rapid
treatment and the expansion of primary PCI to more hospitals
may allow for funding of programs for prehospital ECGs to
be tied in as well.
Summary
Prehospital ECG programs have the potential to improve the
way care is delivered to patients with STEMI in the United
States. Current American Heart Association guidelines recommend that paramedics perform and evaluate a prehospital
ECG routinely on patients with chest pain suspected of
having STEMI (Class IIa, Level of Evidence B).1,3 The central
challenge for healthcare providers is not to simply perform a
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September 2, 2008
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prehospital ECG, but to use and integrate the diagnostic information from a prehospital ECG with systems of care. The
potential savings in time from first medical contact to reperfusion therapy by integrating prehospital ECGs with hospital
systems of care are considerable and clinically relevant. However, the gaps between use under ideal circumstances and in
routine practice remain substantial (Table 3). There are many
logistic barriers, including the need for increased patient use of
EMS; increased EMS capacity; improved education and quality
assurance for EMS providers; improved collaboration among
EMS, emergency departments, and cardiology; improved organization of hospital systems and providers; and improved coordination of regional hospital networks to provide the ideal
patient care rather than optimize market share. It also is apparent
that several financial barriers, including reimbursement and
cost-effectiveness of this diagnostic technology, will need to be
overcome for prehospital ECGs to gain widespread support
across payors, providers, and healthcare systems. But these
barriers are not insurmountable and can be overcome with
dedicated efforts to improving systems of care. Future investigations and policy measures are needed to encourage EMS,
hospitals, and healthcare systems to adopt and maximize the full
potential of this technology, as well as monitor unintended
consequences.
Many of the barriers to the widespread implementation of
prehospital ECGs are being addressed by the American Heart
Association’s Mission: Lifeline, a national initiative launched
in 2007 to improve systems of care for patients with
STEMI.11 Mission: Lifeline’s initial phase includes Emergency Medical Services System Assessment and Improvement. Working in collaboration with EMS organizations on
national and local levels, Mission: Lifeline is conducting a
comprehensive survey to determine EMS capability, policy,
infrastructure, and resources, including prehospital ECG capability and protocols for care of patients with STEMI. On
the basis of the above assessment, the American Heart
Association plans to build and evaluate the appropriate
infrastructure to ideally serve patients with STEMI that is
tailored at the local, regional, or state level. The implementation phase will address funding, training, the potential for
overuse of STEMI services or procedures, and identification
of underserved populations and development of strategies to
mitigate disparities in access to care, as well as evaluation of
existing process measures and patient outcomes.91
Disclosures
Writing Group Disclosures
Other Research
Support
Speakers’
Bureau/
Honoraria
Ownership
Interest
Consultant/
Advisory Board
Other
Name
Employment
Research Grant
Henry H. Ting
Mayo Clinic
ACC*; Mayo Foundation
for Medical Education
and Research*
None
None
None
None
None
Elizabeth H. Bradley
Yale
University
NHLBI†
None
None
VHA*
None
None
David C. Cone
Yale
University
None
None
None
None
None
None
Jeptha P. Curtis
Yale
University
CO Foundation for
Medical Care*
None
None
None
None
None
Barbara J. Drew
UCSF
None
Medtronic Emergency
Response Systems*
GE Healthcare*;
Phillips Medical*
None
GE Healthcare*
None
Penn State
University
None
None
None
None
Senior Science
Editor,
AHA-ECC†
None
UCLA
None
None
None
None
None
None
W. Brian Gibler
University of
Cincinnati
Abbott/iSTAT⫹O7†
None
None
Audicor*;
Siloam*
None
Educational grant
support from
Abbott†; Biosite†;
Bristol-Myers
Squibb†; Daiichi
Sankyo Lilly†;
Otsuka†;
Sanofi-Aventis†;
ScheringPlough†; The
Medicines
Company†
David C. Goff
Wake Forest
University
None
None
None
None
None
None
John M. Field
William J. French
(Continued)
Ting et al
Prehospital ECGs for Acute Coronary Syndrome
1075
Continued
Employment
Research Grant
Other Research
Support
Speakers’
Bureau/Honoraria
Ownership
Interest
Consultant/
Advisory Board
Other
Alice K. Jacobs
Boston Medical
Center
None
None
None
None
None
None
Harlan M. Krumholz
Yale University
None
None
None
None
None
None
University of
Michigan
AHRQ†
None
None
None
None
None
Robert E. O’Connor
University of
Virginia Health
System
None
None
None
None
None
None
Jeremiah D. Schuur
VAMC and Yale
University
None
None
None
None
None
None
Name
Brahmajee K.
Nallamothu
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This table represents the relationships of writing group members that may be perceived as actual or reasonably perceived conflicts of interest as reported on the
Disclosure Questionnaire, which all members of the writing group are required to complete and submit. A relationship is considered to be “significant” if (a) the person
receives $10 000 or more during any 12-month period, or 5% or more of the person’s gross income; or (b) the person owns 5% or more of the voting stock or share
of the entity, or owns $10 000 or more of the fair market value of the entity. A relationship is considered to be “modest” if it is less than “significant” under the
preceding definition.
*Modest.
†Significant.
Reviewer Disclosures
Reviewer
Employment
Research
Grant
Other Research
Support
Speakers’
Bureau/Honoraria
Expert
Witness
Ownership
Interest
Consultant/Advisory
Board
Other
Elliott M. Antman
Brigham and Women’s
Hospital
None
None
None
None
None
None
None
Eric Bates
University of Michigan
None
None
None
None
None
None
None
James V.
Dunford
University of California,
San Diego
None
None
None
None
None
None
None
This table represents the relationship of reviewers that may be perceived as actual or reasonably perceived conflicts of interest as reported on the Disclosure
Questionnaire, which all reviewers are required to complete and submit.
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